1. Field of the Invention
The present invention relates to a conveyor system for conveying liquid crystal panels, more particularly the present invention relates to a conveyor system having a width adjustment unit.
2. Discussion of the Related Art
Generally, liquid crystal displays are devices that display images using liquid crystal cells arranged in a matrix pattern. Data signals, representative of image information, may be used to selectively control the light transmittance of each of the liquid crystal cells.
Liquid crystal displays are fabricated by forming a plurality of thin film transistor (TFT) substrates within a first substrate, forming a plurality of color filter substrates within a second substrate, bonding the first and second substrates to each other, and cutting the bonded first and second substrates into a plurality of liquid crystal panels, wherein each liquid crystal panel includes a TFT substrate bonded to a color filter substrate.
The TFT substrates are fabricated according to a process including deposition, photolithography, and etching to form an array of TFTs. The color filter substrates are fabricated according to a color filter fabricating process. The liquid crystal panels are fabricated according to a liquid crystal cell fabricating process.
Each of the TFT substrates include a plurality of gate lines arranged at fixed intervals along a first direction, and a plurality of data lines arranged at fixed intervals along a second direction, perpendicular to the first direction. Pixel areas, located at crossings of the gate and data lines, include a plurality of thin film transistors (TFTs) and pixel electrodes.
In order to prevent leakage of liquid outside the pixel areas of each of the color filter substrates, the color filter fabricating process includes a step of forming a black matrix layer in regions of the color filter substrate that do not correspond to the pixel areas. The color filter fabricating process further includes steps of forming red, green, and blue color filters, and an ITO (indium tin oxide) common electrode layer.
After the arrays of TFTs are formed, and after the color filter fabrication process is executed, the liquid crystal cell fabricating process is performed on the first and second substrates as follows.
Referring to FIG. 1, after an alignment material has been coated on the TFT and color substrate portions of the first and second substrates, respectively, an alignment process (1S) is performed on the coated alignment material to uniformly align liquid crystal material to be injected into the cell gap. The alignment process (1S) is performed by pre-cleaning each of the first and second substrates, printing the alignment layer on the TFT and color substrate portions of the first and second substrates, respectively, plasticizing the alignment layers, inspecting the alignment layers, and rubbing the alignment layers.
After the alignment process 1S is completed, a gap formation process is then performed. During the gap formation process, the first and second substrates are cleaned (2S), spacers are dispensed on the first substrate so as to ensure uniformity of the cell gap (3S), sealant is dispensed on each color filter substrate within the second substrate and a liquid crystal injection inlet is formed at an edge portion of each liquid crystal panel (4S), and the first and second substrates are pressed and bonded together (5S).
The bonded first and second substrates are then cut and processed into a plurality of liquid crystal panel (6S).
Subsequently, liquid crystal material is injected through the liquid crystal injection inlet into the cell gap of each of the liquid crystal panels and the liquid crystal injection inlet is then sealed (7S).
Lastly, cut surfaces of the first and second substrates are then polished, and an exterior and electrical failure inspection is performed (8S).
The liquid crystal injection process will now be described in greater detail.
In injecting liquid crystal material, liquid crystal material is provided within a liquid crystal container, the liquid crystal container is loaded into a vacuum chamber, and pressure in the vacuum chamber is reduced, thereby creating a vacuum within the vacuum chamber so that any moisture adhered to the inner surface of the liquid crystal container or any air bubbles in the liquid crystal material are removed.
While maintaining the vacuum within the vacuum chamber, the liquid crystal injection inlet of an empty LC cell contacts, or is dipped into, the liquid crystal material in the liquid crystal container. The pressure of the vacuum chamber is then increased and, due to the pressure difference between the interior of the empty LC cell and the interior of the vacuum chamber, liquid crystal material is injected through the liquid crystal injection inlet into the cell gap.
FIG. 2 illustrates the TFT and color filter substrates 100 and 200, respectively. A plurality of gate lines 50 arranged at fixed intervals along a first direction and a plurality of data lines 60 arranged at fixed intervals along a second direction, perpendicular to the first direction, are formed on the TFT substrate. A plurality of thin film transistors (TFTS) and pixel electrodes are formed in pixel areas 70 defined by the crossing of the gate and data lines 50 and 60, respectively. A plurality of pixel areas 70 generally define an image display area 80. While not shown in FIG. 2, each of the TFTs includes gate and source electrodes formed in respective pixel areas 70 that are connected to corresponding gate and data lines 50 and 60, respectively. Drain electrodes of the TFTs are connected to corresponding to pixel electrodes arranged in corresponding pixel areas 70.
A plurality of the gate and data lines 50 and 60, respectively, are connected to gate pads and data pads 90 and 110, respectively, arranged at a periphery of the array substrate 100.
A shorting bar is provided to facilitate the inspection of the liquid crystal panels to determine if any defective characteristics were imparted to the panel during any of the aforementioned fabricating processes. The shorting bar is removed after fabrication of the liquid crystal device is complete. The shorting bar includes first to fourth sub-shorting bars 120 to 123 that are used to separately inspect odd and even data and gate lines 50 and 60, respectively. The first to fourth sub-shorting bars 120 to 123 extend toward ends of the TFT substrate such that they may couple to external terminals (not shown).
The color filter substrate 200 is slightly smaller than the TFT substrate. A black matrix layer 210 is formed on the color filter substrate 200 for preventing leakage of light in regions outside pixel areas 70. A color filter layer (not shown), common electrode (not shown), column-type spacers (not shown) may also be formed on color filter substrates used in large liquid crystal displays.
The column-type spacers arranged in correspondence with gate and data lines of the TFT substrate. A black matrix rim 220 is provided to prevent leakage of light outside the display area 80.
The TFT and color filter substrates 100 and 200, respectively, are bonded to each other using a sealant (not shown) made of photo-hardening or thermo-hardening resin.
The substrates (e.g., bonded TFT and color filter substrates, bonded first and second substrates, unbonded first and second substrates, etc.) are transported between various fabricating processes (e.g., grinding processes, cleaning processes, etc.) via a variable width conveyor system.
Conveyors systems, such as those illustrated in FIG. 3, include a plurality of rotating rollers 300 having supporting ends 300A spaced apart from each other by a predetermined width. The rotating rollers 300 rotate to convey substrates 100A from one location to another. Edges of the substrates 100A are arranged on and contact supporting ends 300A of the rotating roller 300. The substrates 100A are transported according to the electrical characteristics of the panel area of liquid crystal panels. Static electricity may be generated due to friction caused by contact between the liquid crystal panels and the supporting ends 300A. Accordingly, supporting ends 300A are arranged to contact edges of the liquid crystal panels that include the gate pads or data pads 90 or 110, respectively, and the black matrix rim 220 to thereby minimize the risk of generating static electricity.
Conveyor systems such as those illustrated in FIG. 3, however, are disadvantageous for the following reasons.
During the liquid crystal cell fabricating process, the width between the supporting ends 300A must be optimally adjusted to efficiently transport liquid crystal panels. To adjust the width between the supporting ends 300A, a screw (not shown) is manually turned. In manually turning the screw, the efficiency of the conveyor system is reduced.
Moreover, upon manually turning the screw, the width may be incorrectly adjusted and one of the supporting ends 300A may contact the unit liquid crystal panels in a manner capable of generating static electricity. Static electricity damages the alignment layer and degrades the injected liquid crystal material.
Now making reference to FIG. 4, FIG. 4 illustrates a related art conveyor. Briefly, a conveyor is a machine which transfers materials and goods at a constant distance in succession, and the conveyor is usually used for transfer of components, materials and semiprocessed goods within a factory, for transfer of coal and ore in a mine, and for transfer of sand in a construction site. The conveyor is categorized into a fixed type system of transferring goods having the same size, and an adjustable type system of transferring goods having the different sizes by adjusting a width according to the size of goods. As shown in FIG. 4, the conveyor is provided with a transfer unit 1, conveyor plates 2, and a width adjustment unit. At this time, the transfer unit 1 transfers goods, and the conveyor plates 2 are provided at both sides of the transfer unit 1 to support and guide goods. Also, the width adjustment unit adjusts the width of the conveyor plate 2 to the size of goods.
The transfer unit 1 is provided with a plurality of rollers 1a and a motor (not shown), wherein the plurality of rollers 1a are provided in a goods-traveling direction inside the conveyor plate 2, and the motor (not shown) drives the plurality of rollers 1a. 
Meanwhile, the width adjustment unit is provided with a motor 3a for adjusting the width, a power-transmission bevel gear 3b synchronized with the motor 3a, fixed screw nuts 3c penetrating the conveyor plates provided at both sides of the transfer unit 1, and a shaft 3d having a right-handed screw and a left-handed screw on both sides of a central portion to penetrate the screw nuts 3c and having one end connected with the motor 3a and the power-transmission bevel gear 3b. Also, the screw nut 3c is comprised of a ball nut or a common nut.
In the conveyor having the aforementioned structure, the process of adjusting the width in correspondence with the size of goods will be described as follows. First, as the motor 3a for adjusting the width is driven at the clockwise direction or counterclockwise direction, the bevel gear 3b synchronized with the motor 3a is driven. Then, the shaft 3d connected with the motor 3a and the bevel gear 3b is rotated at the clockwise direction or counterclockwise direction, whereby the conveyor plate 2, to which the screw nut 3c is fixed, widens or narrows according to the size of traveling-goods.
However, in case of the aforementioned width adjustment unit, a pitch is inconstant since the shaft 3d and the screw nut 3c are not processed precisely. As a result, it is difficult to determine a precise position, whereby the width of the conveyor plate is inconstant. Also, if the shaft and the screw nut are processed precisely in the aforementioned width adjustment unit of the conveyor, it causes the rise of fabrication cost. On the process of transferring the goods, even if the shaft and the screw nut are processed precisely, minute particles of lubricant, detergent or foreign matters may be caught in the shaft and the screw nut, so that the shaft and the screw nut may not be driven smoothly. Also, the width adjustment unit of the conveyor has short life span, whereby it is necessary to replace the width adjustment unit with new one at short intervals.